The disclosures in the U.S. patents to Frey, U.S. Pat. Nos. 4,157,739 and 4,357,893 are based on a multi-terrain vehicle having powered front and rear wheels, both of which are sterrable in articulated fashion. These patents also disclose basic body structure housing in the form of a bell or shell-like structure housing a power plant and fan which creates a downward air pressure enabling the vehicle to more readily accommodate varying types of terrain. The foregoing, plus tires with special treads, increase the versatility of the vehicle in the transversing of land or water.
One of the problems encountered in the use of vehicles of the type just referred to is the mounting of the wheels on steering forks. It has been found that a fork requires clearance not only above the wheel or tire but between the top of the fork and the underside of the body, thus increasing the height of the body above the ground. Further, the fork, whether single or double-legged, tends to cause accumulation of mud, etc. between the wheel and the fork leg which requires frequent removal in order for the machine to maintain top performance.
According to the present invention, the forks are eliminated and are replaced, preferably for each wheel, with a split shaft and splined sleeve arrangement. The two sections of the split shaft are preferably splined to mate with the internal splines on the sleeve and are arranged end-to-end on a common axis transverse to the line of travel of the machine. The inner ends of the slidable shafts are spaced axially apart and the outer ends are connected respectively to right and left carriers that are mounted on side supports of the body for relative fore-and-aft movement, moving the shafts respectively with them so that, during steering, the common axis of the shafts and sleeve varies angularly in, for example, a horizontal plane, since the outer end of each shaft, although movable with its carrier is also pivoted to that carrier on, for example, an upright axis.
Another feature is that each sleeve journals a pneumatic-tired wheel, particularly of a specific tread configuration. The wheel is confined against axial shifting relative to the sleeve and thus can partake of axial sliding of the sleeve on the shaft. This action is controlled, however, by linkage means connected preferably to opposite ends of the sleeve and to the fore-and-aft movable carriers, respectively. The arrangement is such that, for instance, rearward movement of the right hand carrier and forward movement of the left hand carrier, as in making a right turn, causes the sleeve and wheel to move toward the right side of the body, thus increasing the wheel clearance or room in which the wheel can be steered and accordingly reducing the steering radius.
A further feature is that the wheels are driven respectively by hydraulic motors. Overall, the inventive design results in a compact, efficient design that improves the performance and versatility of the vehicle, especially in the rather rough environment for which the machine is intended.
Further features and advantages of the invention will become apparent as a preferred embodiment of the invention is disclosed in detail in the ensuing description and accompanying sheets of drawings.